1. Field of the Invention
This invention relates to circuit makers and breakers and, in particular, to an interlocking switch and latch.
2. Description of the Prior Art
Actuator controlled switches to remove electrical power from electronic modules during plug-in and removal from a support frame are known in the art as evidenced by U.S. Pat. No. 3,932,716, issued to S. Mottel et al on Jan. 13, 1976. In the Mottel et al arrangement, a latch and the actuator are pivotally mounted in parallel relation on the module, with the latch engaging a fixed support frame member. During insertion and removal, a lateral extension of the latch engages the actuator to hold the module switch off. When the module is fully engaged, the latch is removably displaced from the actuator whereby the actuator can be pivoted to turn the module switch on and off.
A problem with the above arrangement is that it is possible to remove the module without releasing the latch. Should this occur, the switch continues to be held in the ON state and electrical power continues to be supplied to the module until a complete physical break is made in the connection between the module and the support frame. Failure of the latch and switch interlock, as described, has occurred on numerous occasions in actual field operation with subsequent damage to the connector contacts on the support frame and on the module caused by electrical transients. In addition, failure to prevent electrical power from being supplied to the module until is is properly mated with the connector on the support frame can result in damage to the electronic components carried on the module.
Accordingly, it is one object of the present invention to virtually eliminate contact damage and component failures occasioned by having electrical power supplied to the module during its insertion and removal.
Another object is to ensure the removal of electrical power automatically during module insertion and removal.
A further object of the present invention is to provide a safety interlock arrangement wherein the power switch is normally biased to an OFF state, thereby preventing application of electrical power until the module and support frame connector are properly mated.
Still another object is to have the latch and switch actuator mechanically coupled when the switch is in its ON state such that any attempt to insert or remove a module with the switch in this state automatically breaks the mechanical coupling, permitting the switch bias to return the switch to its OFF state.